British & Irish Lions coach Warren Gatland has admitted that Sam Warburton, a one-time favourites to lead the elite tourists to Australia later this year, is in danger of missing out on selection altogether if he fails to regain his place in the Wales line-up.

Warburton missed Wales' 16-6 victory over France in Paris last weekend with a shoulder injury and is also set to sit out their next Six Nations clash against Italy after interim coach Rob Howley's decision to retain the same starting XV for their date in Rome.

Gatland, who has temporarily stepped down from his usual role as Wales coach while he concentrates on his Lions duties, has refused to interfere with selection but has issued a warning that the Six Nations will heavily influence the make-up of his squad that will be announced at the end of April.

"We're not ruling anyone out but the Six Nations Championship does have quite a significant bearing on selection," Gatland told The Daily telegraph. "Sam is in the same position as a number of players who have not been picked for their national teams. You can understand what Stuart Lancaster is doing with England with the likes of Dylan Hartley and Manu Tuilagi on the bench. Ben Foden is not being picked either. That's Stuart's decision and it's done for a reason. Stuart is rewarding his guys who have performed.

"Sam is in the same boat. There was a good, gutsy performance from Wales in Paris on Saturday and those guys have been rewarded. You can't influence or get involved with what the coaches want to do. That's their prerogative."

Gatland made Warburton the Wales captain ahead of the 2011 Rugby World Cup and the flanker was touted as a potential Lions skipper earlier this season only for his form to desert him in recent months. However, Howley insists he can still force his way into the mix, commenting: "It doesn't affect his Lions chances, not at all," Howley said. "It's not a given that you have to be playing international rugby to play for the Lions or that you have to be captain of your national team to be captain of the Lions."